Construction projects often require the insertion of and removal of elongate members in the earth. Elongate members can take many forms, such as hollow cylinders (pipe piles, caissons), solid cylinders (concrete or wooden piles), and sheets (sheet piles).
To facilitate insertion or removal of an elongate member without excavation, pile driving systems and methods may be used. A pile driving system or method can employs a static or repetitive driving force along a longitudinal axis of the elongate member. A static driving force may be created by weight applied to an upper end of the elongate member and/or a gear drive or the like that applies a crowding force to the elongate member. A repetitive driving force may be created by a drop hammer, diesel hammer, or the like. When directed towards the ground, the driving force can be sufficient to cause the elongate member to enter the ground, depending upon soil conditions and the like. When directed away from the ground, the driving force extracts the elongate member from the ground.
The present invention is directed to a pile driving system or method in which a static driving force is combined with a vibrational force. A vibration system typically applies the vibrational force to the elongate member in combination with a static driving force. Under most conditions, the vibrational force significantly enhances the ability of the pile driving system or method both to insert and to extract an elongate member. When a pile driving system or method employs vibrational forces to insert or extract an elongate member, a vibration suppression system is often used to inhibit transmission of these forces back to a support system (e.g., crane, spotter) used to position the pile driving system and/or elongate member.
To ensure that the vibrational forces are effectively transmitted to the elongate member, clamping system and methods are typically employed. A clamping system or method is typically configured to apply a clamping force that substantially rigidly connects the vibrational device to the elongate member.
A clamping system for a pile driving system or method usually comprises a fixed clamp member and a movable clamp member. The fixed clamp member is substantially rigidly attached to a clamp housing, a portion of the elongate member is placed between the fixed clamp member and the movable clamp member, and the movable clamp member is displaced relative to the clamp housing such that the portion of the elongate member is gripped between fixed and movable clamp members.
The geometry of the clamp members is typically configured based on the geometry and material of the elongate member. For example, clamp members for a metal sheet pile would be generally flat, perhaps with a surface textured to increase friction between the clamp members and the pile. On the other hand, the clamp members for a wooden pile might be curved with teeth that will penetrate the wooden pile to reduce slippage.
One special form of an elongate member is a rebar cage that can be used as a pile by itself or to reinforce a poured concrete pile. A rebar cage typically comprises longitudinal bars and ring bars. The ring bars are welded around longitudinal bars to form a generally cylindrical structure that is hollow and has a discontinuous surface.
The shape and construction of a rebar cage cannot effectively be secured to a vibrational device using conventional clamp assemblies with a fixed and movable clamp member. The need thus exists for improved clamping systems and methods for elongate members such as rebar cages.